Such a gas bag module in which a discharge region can be opened in the gas bag wall when a reduction to the internal pressure of the gas bag is required, is known for example from WO-A-2004/045919. A pyrotechnic charge in the form of a fuse is arranged directly on the discharge region such that the discharge region burns through or is torn open mechanically after the fuse has been ignited.
In the gas bag module shown in WO-A-03/097407 a blast pin is provided in order to expose a tubular discharge region of the gas bag.
In EP-A-1 279 574 a gas bag module is shown in which, in order to expose discharge openings, a slider is moved in a holding piece such that bores formed therein are in alignment with the discharge openings. The hot gas flowing into the gas bag melts the region of the gas bag which is situated between the bores of the slider and the discharge openings in the holding piece, such that a portion of the gas emerges from the gas bag during filling.
A gas bag module is known from U.S. Pat. No. 6,547,274 B in which the opening cross-section of a discharge opening in a carrier plate can be exposed by means of piezoelectrically controlled flaps. The current supply of the piezoelectric elements is controlled for example depending on the posture or physique of the vehicle occupant or on the speed of the vehicle.